diff --git a/GPy/likelihoods/gaussian.py b/GPy/likelihoods/gaussian.py
index 0c73e485..51b56d09 100644
--- a/GPy/likelihoods/gaussian.py
+++ b/GPy/likelihoods/gaussian.py
@@ -99,7 +99,7 @@ class Gaussian(Likelihood):
     def predictive_variance(self, mu, sigma, predictive_mean=None):
         return self.variance + sigma**2
 
-    def predictive_quantiles(self, mu, var, quantiles, Y_metadata):
+    def predictive_quantiles(self, mu, var, quantiles, Y_metadata=None):
         return  [stats.norm.ppf(q/100.)*np.sqrt(var) + mu for q in quantiles]
 
     def pdf_link(self, link_f, y, extra_data=None):